1. Field of the Invention
The present invention relates to a gauge assembly for use in a vehicle instrument cluster.
2. Description of Related Art
Instrument cluster gauges, such as the speedometers, tachometers, fuel and temperature gauges used in modern vehicles, commonly include a pointer body or needle coupled to a permanent magnet. The magnet is generally carried in a plastic housing or bobbin, which is wrapped with wire coils. During operation of the vehicle, current flowing through the coils creates a magnetic field, and the magnet rotates within the housing to align itself in force balanced relationship with the field. Since the pointer body rotates with the magnet, positioning of the pointer body is controlled by the direction and magnitude of the current in the coils. To provide for steady movement of the pointer body, a viscous fluid is carried in the housing to damp the rotational movement of the magnet.
Gauge housings commonly comprise a pair of interlocking housing elements, which together define a chamber for holding the magnet and damping fluid. It is known, for example, to provide one of the housing elements with a receptacle and the other housing element with a plug which fits within the receptacle and forms a chamber therebetween. Typically, the receptacle includes a side wall having a first circumferentially extending mating surface while the plug includes a side wall having a second circumferentially extending mating surface. As is conventional in the fluid handling arts, the mating surfaces each have a generally smooth surface texture. Ideally, the two mating surfaces are joined in a press fit, fluid-tight relationship. In practice, however, the connection is often insufficient to prevent leakage of damping fluid from the chamber. A need therefore exists for a gauge assembly having improved seal means capable of reliably retaining damping fluid within the housing chamber.